PATIENT CHARACTERISTICS: Age: 18 and over Performance status: ECOG 0-2 OR Karnofsky 70-100% Life expectancy: At least 15 weeks Hematopoietic: Granulocyte count greater than 1,500/mm3 Hemoglobin at least 10.0 g/dL Platelet count greater than 100,000/mm3 Hepatic: Bilirubin no greater than 1.5 times upper limit of normal (ULN) SGOT no greater than 3 times ULN Renal: Creatinine no greater than 1.5 mg/dL Cardiovascular: No myocardial infarction within the past 6 months No congestive heart failure requiring therapy Other: Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception HIV negative No active or uncontrolled infection No psychiatric disorders that would preclude study No other severe concurrent disease that would preclude study No frequent vomiting or other medical condition that would interfere with oral medication administration (e.g., partial bowel obstruction) No other malignancy within the past 5 years except adequately treated basal cell or squamous cell skin cancer or carcinoma in situ of the cervix